Simple Harmonic Motion Given Amplitude and Frequency

[Vanessa Avila]

Homework Statement

A cheerleader waves her pom-pom in SHM with an amplitude of 17.3 cm and a frequency of 0.830 Hz .
Find the maximum magnitude of the velocity.

Homework Equations

v = -w Asin(ωt+Φ) = -wx
or
Conservation of Energy:
1/2kx² + 1/2mv² = 1/2kA²

The Attempt at a Solution

I tried v = -ω(x) using 0.173 as x
v = -5.21(0.173) = -0.0901 > wrong

I got the ω by solving for period T (1.205s), i then made this equal to 2π/ω to solve for omega.

I have yet to try the conservation of energy. But what would be the x in this case?

 

[Vanessa Avila]

I just realized that i had an extra 0 there for -0.0901, should have been 0.901!

 

[ehild]

Homework Statement

A cheerleader waves her pom-pom in SHM with an amplitude of 17.3 cm and a frequency of 0.830 Hz .
Find the maximum magnitude of the velocity.

Homework Equations

v = -w Asin(ωt+Φ) = -wx
or
Conservation of Energy:
1/2kx² + 1/2mv² = 1/2kA²

The Attempt at a Solution

I tried v = -ω(x) using 0.173 as x
v = -5.21(0.173) = -0.0901 > wrong

There are to many 0-s. And the magnitude is not negative!

 

[Vanessa Avila]

There are to many 0-s. And the magnitude is not negative!

Thanks! :)

 

[Vanessa Avila]

There are to many 0-s. And the magnitude is not negative!

I do have another question actually. How would i solve this?
"Find the speed when the pom-pom's coordinate is x= 9.40 cm ."

I tried to use the equation v = ωx and got 0. 48974, but i got the wrong answer
v = (5.21rad/s)(0.094m) = 0.4897

 

[ehild]

I do have another question actually. How would i solve this?
"Find the speed when the pom-pom's coordinate is x= 9.40 cm ."

I tried to use the equation v = ωx and got 0. 48974, but i got the wrong answer
v = (5.21rad/s)(0.094m) = 0.4897

The velocity is the time derivative of the displacement. If x=Acos(ωt) what is v=dx/dt?
V=ωA is the relation between maximum displacement and maximum speed.